The present invention relates to infusion pumps and, in particular, to a portable, programmable infusion pump wherein incremental doses of a medicant are delivered at a self-calculated rate and wherein a plurality of modes of operation may be selectively programmed to ensure that a proper total daily profile and dosage is delivered.
Infusion pumps or automatic medicant injecting mechanisms have existed in the prior art for a great many years. Such devices typically comprise a chamber for containing a medicant and means for controllably causing the evacuation of the chamber. Various and sundry control means have been employed and which most typically take the form of electro-mechanical arrangements including motor means, drive means, means for evacuating the chamber and pulse producing means for controllably operating the motor means. Some of the more recent of such systems can be found upon reference to U.S. Pat. Nos. 3,858,581; 4,150,672 and 4,191,187, and which generally show and describe infusion pumps that employ motor means, a transmission system and a lead screw for controllably causing the administration of the doses of the medicant.
In the Whitney U.S. Pat. No. 4,150,672 patent, the medicant is delivered at a rate established in response to individual, fixed width pulses that are produced by an oscillator. Wright in the U.S. Pat. No. 4,191,187 patent also delivers the medicant as per fixed width pulses in response to the actuation/deactuation of a cam and micro-switch that are operatively coupled to the lead screw assembly to control the drive/braking action of the assembly. Kamen in the U.S. Pat. No. 3,858,581 patent, on the other hand, recognizes that uniform pulses are not the same as the uniform displacement of the syringe plunger, due to the number of factors that affect the dosage delivered (i.e. variations in the work load, supply voltage and medicant). Accordingly, Kamen discloses the use of a cam/micro-switch and counter assembly for uniformly displacing the syringe plunger as each dose is delivered to the patient.
Efforts employing digital techniques can also be found upon reference to Franetzki et al in U.S. Pat. No. 4,282,872 and Ellinwood in U.S. Pat. No. 3,923,060. Franetzki generally discloses partially implantable apparatus employing preprogrammed sequences that deliver a selected amount at a rate pursuant to the programmed sequence. Ellinwood, on the other hand, discloses an implantable infusion device that employs a microcontroller that operates in response to a plurality of sensors contained within the body. The pump then dispenses the medicant in accordance with a pre-stored program that is entered either upon implant or via an external programmer.
Nowhere, however, does the prior art disclose the present apparatus and which generally comprises a portable, programmable infusion pump that acts to dispense uniform incremental doses of medicant at a rate determined by the desired dose and concentration, programmed by the patient or doctor. In its preferred embodiment, the present infusion apparatus employs a lead screw along with photo coupling means and a counter for determining the volume of each incremental dose. The number and rate of application of the doses is then determined by the microprocessor, upon entering the concentration and rate.
The above features and advantages of the present invention, as well as further objects thereof, will however become more apparent and more fully appreciated upon reference to the following description and drawings.